Palatine Chapel, Palermo, Sicily
This is the Byzantine style for representing St. Pancras, although with a Latin inscription. This mixing of influences is typical of the chapel, which was built by Roger II, a Catholic but with close ties to Constantinople.
In Orthodox icons the cross held in one hand is an indication of martyrdom.
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Read more about St. Pancras.
Photographed at the chapel by Richard Stracke, shared under Attribution-NonCommercial-ShareAlike license.